1. Field of the Invention
The present disclosure relates to a system for supplying power asymmetrically for downlink transmission through a single transmission passage.
2. Background of the Invention
A low power wireless network includes a node operated by battery power, so transmission power thereof is very low. Thus, in order to transmit data to a node positioned in a remote area, a multi-hop transmission is essential, and to this end, routing techniques have been actively studied.
In particular, an existing low power wireless network solution such as a notification system, or the like, mainly features uplink data transmission, and thus, low power wireless network routing techniques have been developed on the based of uplink. For example, starting from a collection tree protocol (CTP) developed by Stanford University in 2009, routing over low power and lossy network (RPL) was standardized as a low power wireless network routing technique, and has since been steadily researched.
Recently, as demand for a low power wireless network system updating information of numerous objects in real time, such as an electronic shelf label (ESL) system, wireless reprogramming, a library books arrangement system, and the like, is on the rise, the necessity of a downlink data transmission technology has increased. However, research has so far focused on uplink, and thus, a downlink technology level is insufficient, and high reliability of data transmission is not guaranteed due to ineffectiveness.
Also, although the RPL, a low power wireless network standard routing technology, supports basic downlink routing, it has large overhead and cannot effectively cope with a change in a channel, which has, thus, failed to be widely used. Thus, for remote downlink transmission without multi-hop routing, a multi-cell network may be established by dividing a wide range into several cells and performing single hop transmission with a sensor node by a coordinator administering each cell. In this network, however, inter-cell interference is so serious that additional development of technology is required and several coordinators need to be installed.